2018 Volume 82 Issue 11 Pages 409-414
Ternary Nb-Re-Si alloy samples were melted and pulled simultaneously in a tetra-arc furnace and rapidly water-quenched after heat treatment at 1150°C for 1200 h. The microstructures of the samples that had been water-quenched after heat treatment were observed and the Nb, Re and Si concentrations in the constituent phases were measured using an electron probe microanalyzer (EPMA). In the cross-sectional structure of the obtained alloy samples, the lower portion of the pulled part consists of Nb5Si3 and Nb-Re-Si ternary compound phases. By contrast, the upper portion consists of Nb5Si3 and Nb solid solution phases. The Nb solid-solution phase, Nb5Si3 and Nb-Re-Si ternary compound are in equilibrium. It was found that the solubility limit of Si in the Nb solid-solution phase ranges from 0.6 to 1.7 at%, while the solubility limit of Re in the Nb5Si3 phase is 1.3-2.0 at%. The maximum amount of Re in the Nb5Si3 phase in equilibrium with the Nb solid solution is about 0.9 at%.
